The impact of direct oral anticoagulants on viscoelastic testing - A systematic review

[Overdosing of direct oral anticoagulants]

BACKGROUND

Direct oral anticoagulants (DOAC) are increasingly used for prophylaxis and treatment of thromboembolic events. Incorrectly dosed DOAC treatment is associated with excess mortality.

PURPOSE

This article aims at raising awareness of DOAC overdosing and its causes as well as presenting a diagnostic and therapeutic work-up.

MATERIAL AND METHODS

Based on a case presentation, a structured review of the current literature on DOAC overdosing was performed and treatment recommendations were extracted.

RESULTS

In addition to wittingly or unwittingly increased DOAC intake, common causes of overdose are inadequate dose adjustment for concomitant medication or comorbidities. Global coagulation testing should be supplemented with DOAC-specific testing. Severe bleeding and the need for invasive diagnostics or urgent surgery represent indications for treating DOAC overdoses. Based on the cause of an DOAC overdose, active charcoal, endoscopic pill rescue, antagonization with idarucizumab or andexanet alfa and the targeted substitution of coagulation factors represent treatment options.

CONCLUSION

The sensitization of clinicians is important to ensure a timely diagnosis and adequate treatment of DOAC overdosing. This report provides an overview of current knowledge on diagnostics and treatment; however, further studies are necessary to improve the existing algorithms.

Global Hemostasis Testing in Chronic Kidney Disease-Are They Better Predictors of Bleeding and Thrombosis Risk?

Chronic kidney disease (CKD) affects over 10% of the global population and significantly increases the risk of cardiovascular disease as well as arising bleeding. There are alterations in hemostasis, which are multifactorial, involving complex interactions between coagulation, platelets, and the vessel wall. Hemostasis evaluation in CKD is critical for the optimal management of patients. However, conventional coagulation testing and renal function do not fully reflect the hemostatic alterations and do not adequately represent the risk of bleeding and/or thrombosis in patients with CKD. Global hemostatic assays, including thrombin and fibrin generation assays, provide a more wholesome assessment of the process, including the interaction between procoagulants, anticoagulants, platelets, and fibrinolysis. This review critically appraises published studies reporting the use of global coagulation assays to evaluate hemostasis in patients with CKD, as well as associated clinical outcomes.

[Point of care coagulation diagnostics-Absolutely necessary or only a reasonable supplement?]

Point of care (POC) coagulation diagnostics have become an integral part of clinical patient care. In particular, the strengths of POC viscoelastometry (VET) lie not only in the rapid availability of test results but also in the fact that VET provides insights into coagulation that cannot be detected by standard laboratory tests. The relevance of POC-VET in the optimal management of patients with acutely acquired bleeding disorders, such as trauma-induced coagulopathy, is now unquestioned and is also reflected in the corresponding guidelines; however, VET also provides important information about fibrinolysis and fibrinolytic activity and in combination with other laboratory values can possibly also be sensitive for prothrombotic coagulation disorders. Therefore, POC-VET is increasingly being used in intensive care medicine. The use of POC diagnostics is not subject to the same standards as central laboratory testing. In order to maintain high quality and avoid harming patients, the requirements for medical device manufacturers in particular have been increased as part of the in vitro diagnostic reagents (IVDR) regulations, which places high demands on quality management in particular. The variety of POC devices and the lack of comparability between them remains an unsolved problem. It should be critically discussed to what extent medical device manufacturers and pharmaceutical companies could be legally required to keep unique and urgently needed technologies on the market, especially if no comparable alternatives will be available in the foreseeable future. Overall, from today's perspective, the use of POC coagulation diagnostics is essential for optimal patient care.

Ischemic Stroke in Patients Under Oral Anticoagulation: The Achilles Heel of Atrial Fibrillation Management

Oral anticoagulation (OAC) is essential for preventing ischemic stroke events in patients with atrial fibrillation (AF), and leads to a significant ischemic prophylaxis, when appropriately used. However, there is still a risk of experiencing stroke events, despite being under anticoagulation. Stroke despite OAC is an increasingly common diagnosis, and pathophysiologically, it can be associated with several etiologies, ranging from AF competing mechanisms to true anticoagulation failure. While the cardioembolic origin of stroke is the most frequently identified etiology, other factors also have to be considered, as there is a significance risk of coexistence. This highlights the need for thorough diagnostic testing, evaluating each stroke etiology independently, with the use of imaging, biomarker and blood tests. Treating such patients, however, is more complex, as there is still uncertainty regarding the selection of OAC post-stroke, with data showing a superiority of direct OAC (DOAC), compared to vitamin K antagonists, in recurrent ischemic stroke prevention and conflicting results regarding OAC switch. Finally, the additive value of cardiac interventions, such as left atrial appendage occlusion (LAAO), in secondary prevention of stroke, is being explored, as it could potentially lead to significant stroke risk reduction. This review, therefore, provides an updated summary of the pathophysiology, diagnostics and therapeutics of stroke under OAC, while also discussing the future direction on the Achilles heel of AF management.

Measuring Direct Oral Anticoagulant (DOAC) Levels: Applications, Limitations, and Future Directions

INTRODUCTION

There are important challenges with the measurement and interpretation of direct oral anticoagulant (DOAC) anticoagulant effect including a lack of therapeutic ranges, inaccuracy of routinely available coagulation assays, lack of established thresholds for clinically significant effect, and uncertainty about how to apply the results to patient care.

OBJECTIVE

In this narrative review, we provide a practical approach to DOAC measurement in clinical practice.

METHODS

By summarizing the literature and using illustrative cases, we highlight key principles of commonly available tests, outline potential indications for measuring DOAC drug levels, and provide guidance on interpreting results to inform management decisions.

CONCLUSION

While DOACs do not require routine monitoring of anticoagulant effect, assessment of plasma DOAC concentration may be helpful in select emergency and non-emergency clinical scenarios.

Cancer-Related Coagulopathy and Perioperative Considerations

Cancer-related coagulation abnormalities are characterized by complex dysregulation of the hemostatic system, predisposing patients to increased risk of thrombotic and hemorrhagic complications and associated increased morbidity and mortality. Advances in anticancer therapies with improved outcomes have led to better survival and older age of patients living with or having survived cancer. There is also a significant increase in the number of patients diagnosed with cancer. All these factors will increase the number of patients presenting for surgical procedures, both cancer-related and noncancer related. It is important for the anesthesiologist to understand the magnitude of cancer-related coagulation derangement, its types, pathophysiology, and clinical presentation, to optimize the perioperative management of this high-risk rapidly growing patient population.

Validation of a whole blood coagulometer sensitive to the direct oral anticoagulants

Readily available and rapid turn-around, bedside assays to measure the effect of the direct oral anticoagulants (DOACs) are not available. This study evaluates a point-of-care (PoC) coagulometer to assess the anticoagulant effects of the DOACs and low molecular weight heparin. Studies were done in fresh spiked blood from healthy volunteers. PoC coagulometer baseline clotting times were half that of the manual whole blood clotting time (WBCT, legacy method) and exhibited a sensitivity to DOAC anticoagulation approximately twice that of WBCT. All %CV values for both methods were < 10% with most being < 5% indicating acceptable precision of both methods. R2 values for both clotting time and percent rise from baseline were > 0.98 indicating a strong correlation between the two methods. Replicate measurements for all subjects showed a maximum upper %CV value of 5.56% and a maximum upper value of all absolute %Differences of 5.5%, with both criteria meeting predefined acceptance criteria. The dose-response curves for all subjects were linear across the concentration ranges tested. The Perosphere Technology PoC coagulometer detects a range of therapeutic levels of the DOACs apixaban, rivaroxaban, edoxaban, and dabigatran, as well as the low molecular weight heparin, enoxaparin, with high precision and sensitivity. Please check and confirm the processed affiliations are correct . and amend if necessary.

Monitoring Hemostatic Function during Cardiac Surgery with Point-of-Care Viscoelastic Assays: A Narrative Review

Bleeding is a well-known and severe complication of cardiac surgery. Cardiopulmonary bypass, along with heparinization and hemodilution, is thought to affect all pathways of the hemostatic process, leading to excessive bleeding and worsened morbidity and mortality. The traditionally used standard laboratory tests (SLTs) were not designed for the surgical setting, have long turnaround times, and are poor predictors of bleeding. This review aims to give an overview of viscoelastic assays (VEAs), compare VEAs to conventional testing methods, and summarize the evidence for VEAs in cardiac surgery. A search of Medline via Pubmed, Scopus, and Embase yielded 2,868 papers, which we reviewed and summarized the key findings. VEAs such as rotational thromboelastometry and thromboelastography provide a quick turnaround, graphical, global impression of hemostasis in whole blood. VEAs allow for the analysis of specific contributors to the coagulation process and may facilitate cause-oriented hemostatic treatment and the development of treatment algorithms. VEAs have been found to have a high specificity and high negative predictive value for coagulopathic bleeding. Patients treated with VEA-based algorithms have been shown to have lower rates of bleeding, transfusion requirements, and exposure to allogeneic blood products. However, VEA-based algorithms have not demonstrated a mortality benefit and evidence for outcomes such as surgical re-exploration and hospital length of stay remains equivocal. In conclusion, VEAs have been shown to be comparable if not superior to SLTs in cardiac surgery. Further large-scale studies are needed to better evaluate the impact of VEAs on clinical outcomes.

Management of severe traumatic brain injury in a rivaroxaban overdose: illustrative case

BACKGROUND

The management of rivaroxaban overdose in severe traumatic brain injury (sTBI) is undocumented. Reversal with andexanet alfa (AA) and prothrombin complex concentrates (PCCs) in cases of supratherapeutic doses remains unproven. Management is further complicated by the absence of real-time serum rivaroxaban concentration assays and drug-specific coagulation assays. This report details the use of plasma exchange (PLEX) in combination with PCC and AA to manage rivaroxaban overdose in sTBI.

OBSERVATIONS

A 36-year-old female presented with sTBI. Her admission international normalized ratio was 4.8 and thromboelastography reaction time was 85 seconds. Chromogenic low-molecular-weight heparin anti-Xa (AXA) concentration was < 0.1 units/mL. PCC and vitamin K were administered but failed to improve coagulopathy. Further history revealed a possible rivaroxaban overdose, and AA was administered. The second AXA prior to AA was > 1.8 units/mL. AXA remained > 1.8 units/mL 3 hours after AA. PLEX was urgently initiated prior to surgery for drug removal. Serum rivaroxaban concentrations pre- and post-PLEX were 534.6 and 256.8 ng/mL, respectively. A hemicraniectomy was performed without intraoperative or postoperative bleeding complications.

LESSONS

Routine reversal strategies may be insufficient in achieving hemostasis in rivaroxaban overdose. PLEX reduced serum rivaroxaban concentration by 52%. PLEX can be an important adjunct to consider for medical and perioperative management of rivaroxaban overdose. https://thejns.org/doi/10.3171/CASE24475.

A review of the perioperative management of direct oral anticoagulants for pediatric anesthesiologists

BACKGROUND

Although direct oral anticoagulants (DOACs) have been used in the adult population for over a decade, DOACs use has begun to rise in pediatric populations since FDA approval of rivaroxaban and dabigatran, DOACs offer several advantages for pediatric patients, to other anticoagulants, including a similar safety profile, minimal lab monitoring, and ease of administration. The rise in DOAC use has led to an increasing number of pediatric patients managed on DOACs presenting for elective and urgent procedures. Perioperative management of anticoagulation is often challenging for providers due to the lack of expert consensus guidelines and the difficulty in balancing a patient's thrombotic risk with bleeding risk for a given procedure.

AIMS

Using the most up to date literature, we provide a focused review on the perioperative management of DOACs in pediatric patients.

CONCLUSIONS

This work presents a focused review for pediatric anesthesiologists on clinically available DOACs, perioperative monitoring and management of DOACs, as well as options and indications for reversal. While consensus expert practice guidelines are still needed, we hope this work will familiarize perioperative physicians with these agents, recommended uses, and potential perioperative management.

Unexpected normal ROTEM results in protein C deficiency with IVC thrombosis

Protein C deficiency is a hereditary disorder that increases the risk of thrombotic events but has unclear effects on rotational thromboelastometry (ROTEM) analysis. A man in his 60s with a history of protein C deficiency and multiple thrombotic events underwent inferior vena cava (IVC) filter removal, iliocaval thrombectomy and infrarenal IVC placement for IVC-related complete iliocaval and common femoral vein thromboses. A ROTEM analysis showed normal coagulation in NATEM and EXTEM and only a slight shortening in A10 and A20 in INTEM, which was unexpected given his diagnosis of protein C deficiency. Normal results indicate that there is complexity and variability of coagulation to maintain a balanced state even in individuals with underlying coagulation disorders.

Impact of elevated direct factor Xa inhibitor plasma levels on perioperative blood loss in patients undergoing urgent surgery

INTRODUCTION

Data on the perioperative bleeding risk associated with elevated plasma levels of direct factor Xa inhibitors (FXa inhibitors) are limited. This study examines perioperative red blood cell (RBC) loss in patients undergoing urgent surgery with a residual FXa inhibitor level exceeding 100 mcg/L and without preoperative FXa inhibitor reversal.

METHODS

This retrospective analysis includes data from 32 patients who underwent urgent noncardiac surgery between 2018 and 2022. This study aims to analyze perioperative RBC loss in patients undergoing urgent surgery with a residual FXa inhibitor level exceeding 100 mcg/L and without preoperative FXa inhibitor antidote-based reversal or unspecific treatment with 4-factor prothrombin complex concentrate (PCC). All patients were managed using a watch-and-wait strategy.

RESULTS

The last determination of FXa inhibitor plasma concentration prior to surgery showed a median of 245 mcg/L (IQR 144-345), with a median time interval of 3.8 h (IQR 2.4-7.2) before incision. Median RBC loss during surgery was 49 mL (IQR 0-253), 189 mL (IQR 104-217) until POD1 and 254 mL (IQR 58-265) until POD3. Only one patient required intraoperative treatment with 4-factor-PCC and none required reversal with andexanet alfa. Linear regression models found no significant influence of FXa inhibitor plasma levels on intraoperative RBC loss. Rivaroxaban was associated with higher RBC loss until postoperative Day 1 compared with apixaban. No thromboembolic events were observed.

CONCLUSION

Despite markedly elevated plasma concentrations of residual direct FXa inhibitors, perioperative RBC loss was limited in patients undergoing urgent noncardiac surgery. The intraoperative watch-and-wait strategy with selective intraoperative FXa inhibitor reversal or treatment only when required appears to be an appropriate approach.

Should viscoelastic testing be a standard point-of-care test on all intensive care units?

Viscoelastic tests (VETs) have transformed assessment of haemostasis and transfusion practices in trauma, cardiac and liver transplantation centres. Impaired haemostasis is a common problem on the general intensive care unit (ICU), but routine use of VETs is rare. We have accordingly reviewed the evidence to determine whether there is evidence to support the use of VETs as a standard point of care test on all ICUs in assessing and managing patients. The benefits of using VETs in the management of major haemorrhage, namely faster identification of a coagulopathy, in particular early detection of fibrinolysis, and reduced transfusion requirements for blood products have been seen in the general ICU. Validation of treatments algorithms is now required to standardise practice. There is also emerging evidence to support the use of VETs to guide urgent treatment decisions in patients with a coagulopathy or in patients taking anti-coagulants or anti-platelet therapies. We recommend that departments independently review the feasibility of setting up a viscoelastic point of care service which considers the applicability to their patient cohort, the financial cost and the personnel required.

Impact of direct oral anticoagulants on ROTEM® variables; a sample size-calculated experimental study

Direct oral anticoagulants (DOAC) are increasingly common, with bleeding events associated with elevated plasma concentrations. Rotational thromboelastometry (ROTEM), a point-of-care tool for assessing secondary hemostasis, has demonstrated a correlation with increasing concentrations of DOAC. However, previous studies have only partially explored this relationship. The primary aim in the current study was to investigate the impact of increasing rivaroxaban concentrations on clotting time (CT) in the EXTEM assay. The secondary aims were to investigate the impact of increasing rivaroxaban concentrations on clot formation time (CFT) and α-angle (AA) and to investigate the impact of increasing concentrations of dabigatran and apixaban on CT, CFT and AA. Blood from 12 healthy volunteers was spiked to anticipated concentrations of rivaroxaban, dabigatran and apixaban at 0, 50, 100, 200, 500 and 1000 µg/L each. Blood with these varying concentrations was analyzed in four different ROTEM assays and CT, CFT and AA were extracted. CT increased linearly with increasing concentrations of all three DOACs. Rivaroxaban and dabigatran spiked blood showed an increase in CT-EXTEM for the 200-1000µg/L concentrations, compared to baseline, and apixaban for the 500-1000 µg/L concentrations. CFT and AA were affected only in supratherapeutic concentrations for all tested DOACs and primarily in the INTEM assay. Among the tested DOACs, apixaban demonstrated the least impact on CT across all assays. In conclusion, ROTEM-derived CT measurements can serve as surrogate markers for DOAC concentrations.

Assessing Direct Oral Anticoagulants in the Clinical Laboratory

Direct oral anticoagulants (DOACs) have significant advantages over vitamin K antagonists including lack of need for routine laboratory monitoring. However, assessment of DOAC effect and concentration may be important to guide clinical management including need for DOAC reversal, particularly in acute or emergent situations. In this manuscript, the authors describe tests to screen for DOAC presence and tests that have demonstrated equivalence to gold standard testing for quantifying DOAC exposure. They also discuss the effect of DOACs on other coagulation assays and strategies for monitoring unfractionated heparin in patients with concomitant DOAC exposure.

Algorithm for Rapid Exclusion of Clinically Relevant Plasma Levels of Direct Oral Anticoagulants in Patients Using the DOAC Dipstick: An Expert Consensus Paper

BACKGROUND

 With the widespread use of direct oral anticoagulants (DOACs), there is an urgent need for a rapid assay to exclude clinically relevant plasma levels. Accurate and rapid determination of DOAC levels would guide medical decision-making to (1) determine the potential contribution of the DOAC to spontaneous or trauma-induced hemorrhage; (2) identify appropriate candidates for reversal, or (3) optimize the timing of urgent surgery or intervention.

METHODS AND RESULTS

 The DOAC Dipstick test uses a disposable strip to identify factor Xa- or thrombin inhibitors in a urine sample. Based on the results of a systematic literature search followed by an analysis of a simple pooling of five retrieved clinical studies, the test strip has a high sensitivity and an acceptably high negative predictive value when compared with levels measured with liquid chromatography tandem mass spectrometry or calibrated chromogenic assays to reliably exclude plasma DOAC concentrations ≥30 ng/mL.

CONCLUSION

 Based on these data, a simple algorithm is proposed to enhance medical decision-making in acute care indications useful primarily in hospitals not having readily available quantitative tests and 24/7. This algorithm not only determines DOAC exposure but also differentiates between factor Xa and thrombin inhibitors to better guide clinical management.

The Role of Viscoelastic Testing in Assessing Hemostasis: A Challenge to Standard Laboratory Assays?

Viscoelastic testing is increasingly being used in clinical and research settings to assess hemostasis. Indeed, there are potential situations in which viscoelastic testing is reportedly superior to standard routine laboratory testing for hemostasis. We report the current testing platforms and terminology, as well as providing a concise narrative review of the published evidence to guide its use in various clinical settings. Notably, there is increasing evidence of the potential utility of viscoelastic testing for assessment of direct oral anticoagulants, and bleeding associated with chronic liver disease, orthotopic liver transplantation, cardiac surgery, trauma, obstetrics and pediatrics.

Hemostasis Testing in the Emergency Department: A Narrative Review

Routine laboratory screening is typically performed at initial evaluation of the vast majority of presentations to the emergency department (ED). These laboratory results are crucial to the diagnostic process, as they may influence up to 70% of clinical decisions. However, despite the usefulness of biological assessments, many tests performed are inappropriate or of doubtful clinical relevance. This overutilization rate of laboratory testing in hospitals, which represents a significant medical-economic burden, ranges from 20 to 67%, with coagulation tests at the top of the list. While reviews frequently focus on nonintensive care units, there are few published assessments of emergency-specific interventions or guidelines/guidance to date. The aim of this review is to highlight current recommendations for hemostasis evaluation in the emergency setting with a specific analysis of common situations leading to ED admissions, such as suspected venous thrombosis or severe bleeding. We revisit the evidence related to the assessment of patient's hemostatic capacity based on comprehensive history taking and physical examination as well as best practice recommendations for blood sample collection to ensure the reliability of results. This review also includes an examination of various currently available point of care tests and a comprehensive discussion on indications, limitations, and interpretation of these tests.

Management of patients with proximal femur fractures under DOACs

PURPOSE

In the past, preinjury direct oral anticoagulant (DOAC) intake has led to delays in time to surgery (TTS) in patients with proximal femur fractures and delays in surgery have been associated with impaired outcomes. Although healthcare institutions/federal committees have set rules for treatment within 24 h of injury, comprehensive guidelines for the perioperative management of these patients, in particular when on preinjury DOACs, are still lacking. This contribution aims to summarize the current evidence on the safe time window for surgery in patients with proximal femur fractures on preinjury DOACs and to outline therapeutic options if emergency DOAC reversal becomes necessary.

METHODS

Narrative review based upon selective review of the pertinent literature.

RESULTS

For the majority of patients with proximal femur fractures and on preinjury DOACs, early surgery appears safe as soon as medical clearance has been obtained. There may be an increase in the need for blood products but with data not yet conclusive. Work-up including assessment of remaining anticoagulant activity and potential reversal should be restricted to patients at risk for bleeding complications, in particular in the presence of renal/hepatic impairment. Methodology for rapid assessment of DOACs including quantitative/qualitative concentration levels is work in progress. In the case of bleeding, rapidly acting reversal agents are available.

CONCLUSION

Preinjury DOAC use should not routinely delay surgery in patients with proximal femur fractures.

Impact of very low dose rivaroxaban in addition to dual antiplatelet therapy on endogenous fibrinolysis in acute coronary syndrome: The VaLiDate-R study

BACKGROUND

Impaired endogenous fibrinolysis is adverse cardiovascular risk factor in acute coronary syndrome (ACS) patients. Addition of very low dose rivaroxaban (VLDR) to dual antiplatelet therapy (DAPT) reduces cardiovascular events but increases bleeding.

OBJECTIVE

We aimed to assess whether addition of VLDR to DAPT can enhance endogenous fibrinolysis.

METHODS

In a prospective, open-label trial, we assessed endogenous fibrinolysis in whole blood, in 549 patients with ACS using the Global Thrombosis Test (GTT) and Thromboelastography (TEG). Patients (n = 180) who demonstrated impaired endogenous fibrinolysis (lysis time [LT] >2000s with the GTT) were randomised 1:1:1 to (i) clopidogrel 75 mg daily; (ii) clopidogrel 75 mg daily plus rivaroxaban 2.5 mg twice daily; or (iii) ticagrelor 90 mg twice daily, for 30 days, in addition to aspirin. Fibrinolytic status was assessed at 0, 2, 4 and 8 weeks. The primary outcome was the change in LT from admission to week 4. We also measured thrombotic occlusion time (OT) at high shear, and rivaroxaban level.

RESULTS

There was no difference between the groups with respect to LT or clot lysis with TEG, and no change in these parameters compared to baseline during study drug allocation. In the rivaroxaban plus clopidogrel group, OT was prolonged compared to the other groups, although rivaroxaban levels were low, suggesting non-compliance.

CONCLUSION

Addition of rivaroxaban 2.5 mg twice daily to DAPT does not affect endogenous fibrinolysis of thrombus formed at either high or low shear. Further studies are needed to determine whether higher doses of rivaroxaban can favourably modulate fibrinolysis.

CONDENSED ABSTRACT

Impaired endogenous fibrinolysis is a strong risk factor in ACS. We aimed to assess whether adding very low dose rivaroxaban (VLDR) to DAPT can enhance fibrinolysis. Fibrin and clot lysis were assessed in whole blood. ACS patients with impaired fibrinolysis were randomised 1:1:1 to clopidogrel 75 mg daily; clopidogrel 75 mg plus VLDR; or ticagrelor 90 mg twice daily, in addition to aspirin. At 30-days, there was no difference in lysis time between the groups, nor change from baseline. VLDR does not improve fibrinolysis at high or low shear. Further studies are needed to determine whether alternative antithrombotic regimens can enhance endogenous fibrinolysis.

Direct oral anticoagulants in trauma patients

PURPOSE OF REVIEW

Direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. Thus, trauma care providers are facing a steadily raising number of injured patients on DOACs.

RECENT FINDINGS

Despite a predictable pharmacokinetic profile, the resulting plasma levels of trauma patients upon admission and bleeding risks remain uncertain. Therefore, recent guidelines recommend the measurement of DOAC plasma concentrations in injured patients. Alternatively, DOAC specific visco-elastic tests assays can be applied to identify DOAC patients at bleeding risk.Bleeding complications in trauma patients on DOACs are generally higher compared to nonanticoagulated subjects, but comparable to vitamin K antagonists (VKAs). In particular, a traumatic brain injury does not carry an increased risk of intracranial bleeding due to a DOAK intake compared to VKAs. Current studies demonstrated that up to 14% of patients with a hip fracture are on DOACs prior to surgery. However, the majority can be operated safely within a 24h time window without an increased bleeding rate.Specific antagonists facilitate rapid reversal of patients on DOACs. Idarucizumab for dabigatran, and andexanet alfa for apixaban and rivaroxaban have been approved for life threatening bleeding. Alternatively, prothrombin complex concentrate can be used. Dialysis is a potential treatment option for dabigatran and haemoabsorption with special filters can be applied in patients on FXa-inhibitors.

SUMMARY

Current guidelines recommend the measurement of DOAC plasma levels in trauma patients. Compared to VKAs, DOACs do not carry a higher bleeding risk. DOAC specific antagonists facilitate the individual bleeding management.

[Update on point-of-care-based coagulation treatment : Systems, reagents, device-specific treatment algorithms]

Viscoelastic test (VET) procedures suitable for point-of-care (POC) testing are in widespread clinical use. Due to the expanded range of available devices and in particular due to the development of new test approaches and methods, the authors believe that an update of the current treatment algorithms is necessary. The aim of this article is to provide an overview of the currently available VET devices and the associated reagents. In addition, two treatment algorithms for the VET devices most commonly used in German-speaking countries are presented.

Challenges to Laboratory Monitoring of Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) exert anticoagulation effect by directly inhibiting Factor Xa (rivaroxaban, apixaban, and edoxaban) or thrombin (dabigatran). Though DOACs are characterized by fixed-dose prescribing and generally do not require routine laboratory drug-level monitoring (DLM), circumstances may arise where the DLM may aid in clinical decision-making, including DOAC dose adjustment, anticoagulant class change, or decisions to withhold or administer reversal agents. We review the current literature that describes high-risk patient groups in which DLM may be beneficial for improved patient anticoagulation management and stewardship. The review also summarizes the limitations of conventional coagulation testing and discuss the emerging utility of quantitative methods for routine and rapid emergent evaluation of DOAC drug levels-in particular, the Anti-Xa activity to detect Factor Xa Inhibitors (rivaroxaban, apixaban, and edoxaban). Both technical and regulatory barriers to widespread DLM implementation are limiting factors to further clinical research that must be overcome, in order to propose universal DOAC DLM strategies and provide clinical-laboratory correlation to formally classify high-risk patient groups.

Antithrombotic and prohemorrhagic actions of different concentrations of apixaban in patients exposed to single and dual antiplatelet regimens

We evaluated modifications in the hemostatic balance of different concentrations of apixaban (APIX) in 25 healthy donors and 53 patients treated with aspirin (ASA, n = 21), ASA and clopidogrel (ASA + CLOPI, n = 11), or ASA and ticagrelor (ASA + TICA, n = 21). Blood samples from participants were spiked ex vivo with apixaban 0 (APIX0), 40 (APIX40), and 160 ng/mL (APIX160). We assessed the effects of APIX on (1) clot formation, by ROTEM thromboelastometry; (2) thrombin generation primed by platelets; and (3) platelet and fibrin interactions with a thrombogenic surface, in a microfluidic model with circulating blood. APIX caused dose-related prolongations of clotting time with minimal impact on other ROTEM parameters. Thrombin generation was significantly inhibited by APIX160, with ASA + TICA actions showing the strongest inhibition (p < 0.01 vs APIX0). Microfluidic studies showed that APIX160 was more potent at suppressing platelet and fibrin interactions (p < 0.001 vs. APIX0). APIX40 demonstrated a consistent antithrombotic action but with a favorable protective effect on the structural quality of fibrin. APIX potentiated the antithrombotic effects of current antiplatelet regimens. APIX at 40 ng/mL, enhanced the antithrombotic action of single or dual antiplatelet regimens but was more conservative for hemostasis than the 160 ng/mL concentration.

The Year in Coagulation and Transfusion: Selected Highlights from 2022

This is an annual review to cover highlights in transfusion and coagulation in patients undergoing cardiovascular surgery. The goal of this article is to provide readers with a focused summary of the most important transfusion and coagulation topics published in 2022. This includes a discussion covering the management of anemia and red blood cell transfusion, the management of factor Xa inhibitors, updates in coagulation testing, updates in the use of factor concentrates, advances in platelet therapy, advances in anticoagulation management of patients on extracorporeal membrane oxygenation and other forms of mechanical circulatory support, and advances in the diagnosis and management of heparin-induced thrombocytopenia.

Amplified inhibition of atherosclerotic plaque-induced platelet activation by glenzocimab with dual antiplatelet therapy

BACKGROUND

Aspirin and platelet P2Y12 inhibitors, such as ticagrelor, suboptimally inhibit microvascular thrombosis during ST-elevation myocardial infarction. Glycoprotein (GP) IIb/IIIa inhibitors may further inhibit this but cause excessive bleeding.

OBJECTIVES

We investigated whether combination of glenzocimab, a GPVI inhibitor, with aspirin and ticagrelor provides additional antithrombotic effects, as GPVI has a critical role in atherothrombosis but minimal involvement in hemostasis.

METHODS

We investigated the effects of glenzocimab (monoclonal antibody Fab fragment) using blood from healthy donors and patients with acute coronary syndrome treated with aspirin and ticagrelor. Platelets were stimulated with multiple agonists, including atherosclerotic plaque, from patients undergoing carotid endarterectomy.

RESULTS

Aspirin and ticagrelor partially inhibited atherosclerotic plaque-induced platelet aggregation by 48% compared with control (34 ± 3 vs 65 ± 4 U; P < .001). Plaque-induced platelet aggregation, adhesion, secretion, and activation were critically dependent on GPVI activation. Glenzocimab alone reduced plaque-induced aggregation by 75% compared with control (16 ± 4 vs 65 ± 4 U; P < .001) and by >95% when combined with aspirin and ticagrelor (3 ± 1 vs 65 ± 4 U; P < .001). Glenzocimab reduced platelet aggregation, adhesion, and thrombin generation when added to blood of aspirin- and ticagrelor-treated patients with acute coronary syndrome. Glenzocimab shared several antithrombotic effects with the GPIIb/IIIa inhibitor eptifibatide with less effect on general hemostasis assessed by rotational thromboelastometry. In a murine intravital model of ST-elevation myocardial infarction, genetic depletion of GPVI reduced microvascular thrombosis.

CONCLUSION

Addition of glenzocimab to aspirin and ticagrelor enhances platelet inhibition via multiple mechanisms of atherothrombosis. Compared with a GPIIb/IIIa inhibitor, glenzocimab shares multiple antithrombotic effects, with less inhibition of mechanisms involved in general hemostasis.